feat: init fitness-coach (backend + miniprogram)

- backend: NestJS service with exercise/plan data
- miniprogram: WeChat mini program client
- exclude node_modules, dist, runtime data-store, local env

miniprogram/sitemap.json

@@ -0,0 +1,8 @@
+{
+  "rules": [
+    {
+      "action": "allow",
+      "page": "*"
+    }
+  ]
+}